DIELECTRIC-PROPERTIES OF CELLULOSE-ACETATE REVERSE-OSMOSIS MEMBRANES IN AQUEOUS SALT-SOLUTIONS

The dielectric properties were studied of cellulose acetate asymmetric membranes in aqueous electrolyte solutions. The value of the membrane capacitance was 395 nF/cm2, which was attributed to the dense layer in the asymmetric membrane. The thickness of the dense layer was calculated to be 27 nm from the value of the membrane capacitance. The membrane conductance depended on the type of electrolyte, while the membrane capacitance remained almost unchanged irrespective of the kind of electrolyte. The dependence of membrane conductance on the type of electrolyte showed that more highly hydrated ions were only capable of permeating the membrane with more difficulty. © 1990.